The objective of the proposed research project is to assess the possible roles of humoral and cellular immunity to tumor antigens (idiotypic determinants of myeloma proteins ) in the suppression of plasma cell growth in mice. Two general approaches will be followed. First, the sera from mice immunized with various myeloma proteins will be examined for the presence of antibody that can bind to corresponding tumor cells, and its role in suppression of tumor growth in mice will be analyzed by the passive administration of specificantibody & neutralization tests. Second, the role of cellular immunity in vivo will be studied by adoptive transfer experiments utilizing spleen cells of immunized animals, and in vitro by the macrophage migration inhibition as well as lymphocyte mediated cell cytotoxicity tests and antibody mediated lymphocyte cytotoxicity tests.